TCP Wrappers Lab — Linux Security

📖 What are TCP Wrappers?

TCP Wrappers use two files to control which hosts can connect to network services:

/etc/hosts.allow — rules evaluated first. Matching connections are permitted.

/etc/hosts.deny — rules evaluated second. Matching connections are rejected.

Rule format: daemon : client
Example: sshd : 10.0.0.5

Step 01

Explore the System

View the current (empty) state of hosts.allow and hosts.deny.

Step 02

Allow SSH from trusted IP

Add a rule to hosts.allow so only 192.168.1.50 can reach sshd.

Step 03

Deny All Others

Add a deny-all rule to hosts.deny to block every other source.

Step 04

Test & Verify

Simulate SSH connection attempts from different IPs to verify your config.

Step 1 — Explore the System

This simulated Linux system has SSH running. Your job is to configure TCP Wrappers so that only 192.168.1.50 can connect via SSH, and all other hosts are denied.

Current Objective: Use the file tabs below to inspect the current state of /etc/hosts.allow and /etc/hosts.deny. Both are empty — no rules are defined yet.

📄 /etc/hosts.allow

📄 /etc/hosts.deny

Add a new rule to /etc/hosts.allow

TERMINAL OUTPUT

Welcome to SecLab — TCP Wrappers Lab Environment

Host: seclab-vm01 | OS: Ubuntu 22.04 LTS | Service: sshd (running)

─────────────────────────────────────────────────────

Inspect /etc/hosts.allow and /etc/hosts.deny to begin.

Step 1 — Explore the System

Lab Complete!